As known, there is an increasing demand from the market for soft drinks or beverages containing fruit particles or pieces, such as soft fruit bits, normally available in cubes or slices, fruit fibers, containing large portions of fruit cellulose, and fruit sacs, i.e. intact “pouch-like” structures of a citrus fruit, filled with or without liquid.
These kinds of beverages are normally stored in tanks before being delivered to the filling machines and then closed and sealed into receptacles for retail.
In order to prevent the deterioration and the degradation by microbial contamination of the pourable products and to prolong the maximum preservation times, it is often necessary to use filling machines which fill the receptacles in aseptic or ultra-clean conditions.
In general, such a filling machine is fed with aseptic or ultra-clean receptacles (for example receptacles which have previously been sterilised) and is adapted to provide receptacles filled with a sterilised product in aseptic or ultra-clean conditions.
A commonly-known filling machine basically comprises a carousel conveyor rotating about a rotation axis, a tank containing the product, and a plurality of filling units which are selectively connected with the tank and are supported by the carousel conveyor in a radially external position with respect to the rotation axis of the carousel conveyor itself.
In one possible solution, each filling unit comprises a filling valve adapted to feed the pourable product to a respective receptacle, a batcher valve interposed between the tank and the filling valve and connected to the latter through an intermediate conduit, and a dosing actuator connected to the intermediate conduit in a position interposed between the batcher valve and the filling valve.
With this type of filling unit, the filling of each receptacle is carried out in two steps.
First, the filling valve is set in a closed configuration, the batcher valve is opened and the dosing actuator is activated to suck the pourable product from the tank via the batcher valve up to reach a desired volume.
At this point, the batcher valve is closed, the filling valve is opened and the dosing actuator feeds the volume of product previously formed to the respective receptacle.
In another possible solution, each filling unit only comprises a filling valve directly connecting the tank with the receptacle to fill. In this case, dosage of the pourable product is done on the basis of the time during which the filling valve is maintained open.
In both cases, each of the above-mentioned filling and batcher valves basically comprises:                a tubular body defining a flowing channel for the pourable product and terminating with at least one narrowed end mouth; and        a shutter movably sliding within the flowing channel between a closed position, in which the shutter sealingly closes the narrowed end mouth and interrupts the flow of the pourable product, and an open position, in which a gap is established between the shutter and the narrowed end mouth so as to allow free flow of the pourable product through such narrowed end mouth.        
In order to avoid any risk of external contamination, the movements of the shutter within the flowing channel are magnetically controlled. In practice, the shutter is magnetically coupled to a driving actuator arranged completely external to the tubular body. More specifically, the driving actuator is provided with one or more permanent magnets and is mounted onto the outer surface of the tubular body in a sliding manner; in a completely equivalent manner, the shutter is provided with one or more permanent magnets facing the respective permanent magnets of the driving actuator and magnetically attracted by the latter through the lateral wall of the tubular body. In this way, any axial displacement of the driving actuator produces a corresponding axial movement of the shutter.
This type of solution is disclosed for instance in WO 2013/057695 in the name of the same applicant.
In this case, the shutter comprises a substantially cylindrical main portion, sliding within the tubular body, and a closing head adapted to sealingly engage the narrowed end mouth of the tubular body in the closed position of the shutter itself.
More specifically, the main portion of the shutter integrally comprises a central cylindrical body, provided with the permanent magnets and housed with a radial gap within the tubular body, and a plurality of protrusions, projecting radially from the cylindrical body at different axial heights thereof and sliding in use along the inner surface of the tubular body itself.
In practice, the annular space between the cylindrical body of the shutter and the tubular body defines the passage for the pourable product with the solid particles; the radial projections of the shutter are so shaped and positioned to not hamper the flow of the particles.
This recently-proposed solution still leaves room for further improvements, especially as to achieve a further increase of the product passage section between the tubular body and the shutter of the valve without reducing the force of magnetic attraction between the driving actuator and the shutter itself.